This disclosure relates generally to methods and devices for use in treating glaucoma. The mechanisms that cause glaucoma are not completely known. It is known that glaucoma results in abnormally high pressure in the eye, which leads to optic nerve damage. Over time, the increased pressure can cause damage to the optic nerve, which can lead to blindness. Treatment strategies have focused on keeping the intraocular pressure down in order to preserve as much vision as possible over the remainder of the patient's life.
Past treatment has included the use of drugs that lower intraocular pressure through various mechanisms. The glaucoma drug market is an approximate two billion dollar market. The large market is mostly due to the fact that there are not any effective surgical alternatives that are long lasting and complication-free. Unfortunately, drug treatments need much improvement, as they can cause adverse side effects and often fail to adequately control intraocular pressure. Moreover, patients are often lackadaisical in following proper drug treatment regimens, resulting in a lack of compliance and further symptom progression.
With respect to surgical procedures, one way to treat glaucoma is to implant a drainage device, or shunt, in the eye. The drainage device functions to drain aqueous humour from the anterior chamber and thereby reduce the intraocular pressure. The drainage device is typically implanted using an invasive surgical procedure. Pursuant to one such procedure, a flap is surgically formed in the sclera. The flap is folded back to form a small cavity and a shunt is inserted into the eye through the flap. Such a procedure can be quite traumatic as the implants are large and can result in various adverse events such as infections and scarring, leading to the need to re-operate.
The following references describe various devices and procedures for treating glaucoma: U.S. Pat. No. 6,827,700 to Lynch, U.S. Pat. No. 6,666,841 to Bergheim, U.S. Pat. No. 6,508,779 to Suson, U.S. Pat. No. 6,544,208 to Ethier, U.S. Pat. No. 5,601,094 to Reiss, U.S. Pat. No. 6,102,045 to Nordquist, United States patent application Ser. No. 2002/0156413 to Williams, 2002/0143284 to Tu, 2003/0236483 to Ren, 2002/0193725 to Odrich, 2002/0165478 to Gharib, 2002/0133168 to Smedley, 2005/0107734, 2004/0260228 to Lynch, 2004/0102729 to Haffner, 2004/0015140 to Shields, 2004/0254521 to Simon, and 2004/0225250 to Yablonski. The aforementioned references are all incorporated herein by reference in their entireties.
Current devices and procedures for treating glaucoma have disadvantages and only moderate success rates. The procedures are very traumatic to the eye and also require highly accurate surgical skills, such as to properly place the drainage device in a proper location. In addition, the devices that drain fluid from the anterior chamber to a subconjunctival bleb beneath a scleral flap are prone to infection, and can occlude and cease working. This can require re-operation to remove the device and place another one, or can result in further surgeries. In view of the foregoing, there is a need for improved devices and methods for the treatment of glaucoma.